Ang, Russell; Seberry, Jennifer; and Wysocki, Tadeusz, 2006, Inequivalence of Nega-cyclic +-1 Matrices, Journal of Combinatorial Mathematics and Combinatorial Computing, 56, 17-32.
We study nega-cyc1ic ±1 matrices. We obtain preliminary results which are then used to decrease the search space. We find that there are 2, 4, 9, 23, 63, and 187 ip-equivalence classes for lengths 3, 5, 7,9, 11, and 13 respectively. The matrices we find are used in a variant given here of the Goethals-Seidel array to form Hadamard matrices, the aim being to later check them for suitability for CDMA schemes.